In recent years, there has been a call for qualitative research in addition to quantitative research. When we can observe that a change occured within therapy, it is interesting to understand what this transformation has been and to grasp the cause of this change. The latter is a question that also concerns analysts and for which Lacan has developed a specific research method: the procedure of the pass. We believe that the testimonies of the pass can be an interesting addition to study Lacanian psychoanalysis. The purpose of this article is to review this procedure. What is this procedure and what are the historical and theoretical frameworks. We provide a brief illustration and some critical notes in this procedure.